Landing navigation is an important part of flight safety. With the incredibly intense construction around the airport, the multipath reflection caused by buildings surrounded has a serious influence on the accuracy of navigation information. From the perspective of the antenna radiation pattern, the ideal antenna radiation pattern is possessed by the model of localizer antenna which is based on the binary antenna array. Taking the reflection of buildings as an example, the antenna radiation pattern under multipath effect is obtained according to the principle of antenna mirroring. The simulation comparison results show that the multipath effect of the building causes the directionality of the heading signal to deteriorate and the amplitude to jump sharply. Based on the advanced trainer on localizer, the major cause of the poor navigation information of the new airport is found out through carrying out the signal verification simulation of approach flight and arc flight respectively and analyzing the influence of multipath affection on the channel difference in depth of modulation value and navigation signal range.